Home yogurt/cheese making machine

ABSTRACT

A kitchen appliance for preparing yogurt, soft frozen yogurt and ice cream, hard frozen yogurt and ice cream, and cheese. The appliance includes a housing having a base and side walls defining an open top. A motor-driven paddle device is rotationally journaled with respect to the cover and base and the motor therefor is adapted to be driven either continuously or with a predetermined duty cycle, dependent upon the product being made. Also mounted on either the cover or the base is a vent hole occluder that is normally positioned to block the vent holes in the cover or base, but which shifts to a second position uncovering those vent holes when the consistency of the product being produced, as tested by the paddle motion or other apparatus reveals that a predetermined cultured state has been reached. Shifting of the occluding device from the covering position to the open position also actuates a switch to shut off the drive motor and a warming element. When a frozen yogurt product is desired, a pre-chilled freezing bowl can be placed in the housing and the paddle used to scrape the frozen yogurt from the walls of the freezing bowl.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of application Ser. No. 08/872,009, filedJun. 9, 1997, now U.S. Pat. No. 5,829,344 and entitled "HomeYogurt/Cheese Making Machine".

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates generally to kitchen appliances, and moreparticularly to a machine for automatically preparing any one of yogurt,soft frozen yogurt, hard frozen yogurt and cheese, at home.

II. Discussion of the Prior Art

Because of its taste and nutritional value, yogurt has been anincreasingly popular food product. Many brand name yogurt products areavailable to the consumer in supermarkets. Traditionally, and because ofthe expense of these products, some consumers attempt to make yogurt athome. Warming devices for making yogurt at home are available and arediscussed in the prior art. For example, U.S. Pat. No. 4,009,368 toFaivre et al. describes an electrically heated yogurt-making machinehaving an enclosure containing a receptacle into which boiled milk and ayogurt starter is placed. The enclosure contains an electrical heatingelement and a fusible material (wax) which is adapted to be heated to amelting point by the heating element. Heat from the melted wax istransferred to the milk container. The purpose of the wax is to providea thermal mass exhibiting a temperature plateau at or near the optimumfor incubating the bacteria used to transform the milk to yogurt.

The yogurt making process requires that the yogurt mix incubaterelatively undisturbed for a somewhat unpredictable number of hoursuntil the desired consistency and acidity is achieved. More frequentdisturbance results in curdling of the milk product and the formation ofcheese. If too high a temperature is employed, it accelerates theprocess to the point where it is difficult to catch the end-point whereconsistency and flavor are at their optimum. Traditional, home-based,room temperature yogurt techniques are slow, sometimes taking as long as12 hours. The room temperature yogurt process does, however, offer theadvantage of allowing it to be checked at reasonable intervals so thatthe incubation process might be terminated at or near its optimal pointby initiating cooling. The incubation process can be accelerated to onlyabout four hours by providing a warm environment for the yogurt mix, butif the optimal point is not detected accurately, the yogurt becomes moreacidic and less palatable. Thus, considerable operator attention andcare is required with prior art warming apparatuses.

The yogurt making appliances of the present invention obviate theseproblems. Specifically, the yogurt making machines of the presentinvention require no operator intervention or monitoring during thereasonably rapid, heating, cooling and warmed incubation process. Thewarming is automatically stopped at the desired point in the processwith refrigeration being initiated automatically to terminate furtherincubation.

A further object and advantage of the present invention is that the samemachine can be used to facilitate the preparation of frozen yogurt andice cream as well as both cultured and artificially curdled cheeseproducts.

SUMMARY OF THE INVENTION

The yogurt making appliances constructed in accordance with the presentinvention are particularly adapted for use in the home to automaticallymake yogurt, hard and soft frozen yogurt or ice cream and cheeseproducts. There are at least six possible embodiments of these devices.The first, motor and detent (magnet) on top, is claimed in theabove-referenced U.S. application and in European Union patentapplication 08/3043720. A second embodiment, motor and detent on thebottom, the third, motor on top and detent on the bottom, the fourth,motor on the bottom and detent on top, the fifth, motor and detent onthe bottom with a center post and the sixth, motor on the bottom anddetent on top with a center post, are described in the presentspecification.

The first embodiment, motor and detent on top, has an insulatedcontainer having a base and peripheral side walls defining anon-circular cross-section and an open top through which milk or driedmilk and water is added to a yogurt starter, usually yogurt from thesupermarket or a remanent of a previous batch.

One or more of (i) either the peripheral side walls, (ii) the base ofthe insulated container, and/or (iii) the paddle member have embeddedtherein or otherwise support an electrical or other warming element,such as a reversible, thermoelectric heating and cooling device and/or anicrome filament that is adapted to apply warming to the contents of thecontainer.

A cover member is configured to fit atop the peripheral side walls incovering relation to the open top of the container. The cover memberincludes at least one vent hole formed therethrough, along with acentrally located hole that is adapted to receive a paddle support shafttherethrough. The paddle support shaft has a rotating paddle secured toits lower end and the shaft for the paddle is sufficiently long so thatwhen the paddle is disposed within the yogurt or cheese mix in thecontainer, the shaft will pass upwardly through the central hole in thecover member.

Also disposed about the paddle support shaft and positioned atop thecover member is a rotatable occluding means for selectively covering andopening the vent hole(s) in the cover member. The means for selectivelyoccluding and opening the vent hole(s) is releasibly secured to thecover member by a detent, such that a predetermined force must beapplied to the vent hole occluding means before it is able to moverelative to the cover member.

Finally, at least one drive motor with a built-in gear reductiontransmission is affixed to the vent hole occluding means for rotatingthe paddle support shaft and paddle relative to the stationary containerto periodically test the contents in the container. When the paddlestalls due to gelling and thickening of the contents, the motor thencauses the occluding means to move from a vent hole occluding positionto an open position. The motor is adapted to be driven either withpredetermined duty cycles or continuously, dependent on the productbeing made.

Shifting of the occluding device from the covering position to the openposition also triggers a switch, shutting off the motor, timer and thewarming element and activating a cooling element. Alternatively, if theoptional vent cover is not utilized, then cooling can rapidly occur ifthe device is disposed in a household refrigerator with its electricalcord extending out past the conventional, soft, door seal gasket used inmost refrigerators.

The culturing container may, as an option, contain a double walledfreezing bowl having a cylindrical, microwave heatable stainless steelinterior wall and a non-cylindrical outer wall when preparing frozenyogurt.

The second embodiment has its motor and detent beneath a rotatable,un-insulated, non-circular culturing container. A double walled freezingbowl having a microwave heatable stainless steel inner wall may beenclosed within the culturing container and both disposed within aninsulated chamber, consisting of a housing, base and cover. The housingalso supports a fixed, downwardly directed, heatable paddle that extendsinto the mix. The base incorporates an air vent opening and/or anelectrical or other warming element, such as a reversible thermoelectricwarmer/cooler, with fans, mounted therein. A centrally located hole isformed through the base that is adapted to receive a drive shafttherethrough from a motor mounted on a rotatable occluding member. Agear reduced electrical motor is carried by the occluder for driving theculturing container. The occluding member is movable from a firstposition in which the air vent in the base is occluded to a secondposition in which the air vent opening is uncovered. The movement occurswhen the consistency of the product being produced, as tested by thecontainer motion, increases the resistance of the container to rotationrelative to the stationary paddle. The means for selectively occludingand opening the vent hole is releasibly secured to the base member by adetent, such that a predetermined force must be applied to the vent holeoccluding means before it is able to move relative to the base member.The motor is adapted to be driven either with a predetermined duty cycleor continuously, depending on the product being made. Shifting of theoccluding device from the vent hole covering position to the openposition also actuates a switch for deactivating the drive motor and thewarming and timing elements and activating the cooling element.Alternatively, cooling can rapidly occur if the optional vent cover isnot utilized and the device is disposed in a conventional refrigeratorwith its electrical cord extending outward past the soft door sealgasket, as with the first embodiment.

The third embodiment has the motor on the top of the container and thedetent located in the base. It, too, has a rotatable, non-circularculturing container designed to be used with or without a freezing bowl.The culturing container is enclosed within a fixed insulated chamber,consisting of an exterior housing, a base and a cover. The cover, whichis fixed to the housing, has a centrally located hole that is adapted toreceive a paddle support shaft therethrough.

The paddle support shaft has a heatable paddle secured to its lower end.The shaft for the paddle is sufficiently long so that, with the paddledisposed within the mix in the container, the shaft will pass upwardlythrough the central hole in the cover member.

At least one drive motor with a gear reduction mechanism is affixed tothe cover for rotating the paddle support shaft and paddle relative tothe container to periodically test the contents of the container.Electrical slip rings permit warming and heating of the rotating paddle.At least one mix-adding hole and/or automatic yogurt starter addinghole, with a plug, is also formed through the cover.

The base incorporates an air vent opening. A centrally located holeformed in the base is adapted to receive a supporting shaft to which thecontainer and the occluder are joined. The container and occluder arejointly movable only from a first position occluding the air ventopening to a second position in which the air vent opening is uncovered.This occurs when the consistency of the product being produced, astested by the paddle motion relative to the mix in the container orfreezing bowl, increases the resistance to paddle rotation sufficientlyto overcome the force exerted by the detent means used to releasiblysecure the yogurt container (and/or freezing bowl) and occluding memberto the base.

The paddle motor is adapted to be driven either according to apredetermined duty cycle or continuously, according to the product beingmade. Shifting of the container and occluding member from the coveringposition to the open position also actuates a switch, shutting off thedrive motor and timer and the thermoelectric warming element andactivates the cooling element. Alternatively, cooling can rapidly occurif the optional vent cover is not utilized and the device is disposed ina refrigerator with the yogurt maker's electrical cord extending outwardpast the soft door seal gasket.

In a fourth embodiment, the motor is disposed in the base and the detentmechanism is on the top. It incorporates a rotatable culturingcontainer, and optionally, a double-walled freezing bowl having anon-circular exterior and a stainless steel inner wall. Either or bothare adapted to be enclosed within an insulated chamber consisting of afixed, insulated, exterior housing, a base member and a cover. The coveris configured to fit firmly atop the housing and it includes at leastone vent hole with an optional cover, and at least one pluggable mixadding hole. The cover also has a centrally located hole containing abearing for journaling a paddle support shaft. The paddle support shafthas a paddle secured to its lower end and the shaft for the paddle issufficiently long so that with the paddle disposed within the mix in theculturing container, the shaft will pass upwardly through the bearing inthe cover member.

Also attached firmly to the paddle support shaft and positioned inrelation to the cover member is a means for selectively occluding andopening the vent hole in the cover member. The means for selectivelyoccluding and opening the vent hole is releasibly secured to the covermember by a detent, such that a predetermined force must be applied tothe vent hole occluding means before it is able to move relative to thecover member. A coiled conductive ribbon or otherwise supple electricalwire connection serves to conduct electricity to the paddle forwarming/heating same.

The base contains an electrical heating element and/or a reversiblethermoelectric warmer/cooler mounted therein. A motor with reductiongears is connected in driving relation with respect to the container.The occluding member mounted on the cover is movable with respect to thecover from a first position in which the air vent opening in the coveris occluded to a second position in which the air vent opening in thecover is uncovered. This again occurs when the consistency of theproduct being produced, as tested by the container motion, increases theresistance to rotation of the container against the paddle. The motor isadapted to be driven either according to a predetermined duty cycle orcontinuously, depending on the product being made. Shifting of theoccluding device from the covering position to the open position alsoactivates a switch, cutting off the drive motor and the warming elementand activating a cooling element. Alteratively, cooling may rapidlyoccur if the optional vent cover is not utilized, and the device isdwelling in the refrigerator as previously explained.

In the fifth embodiment, the motor and detent are disposed in the unit'sbase. It has an insulated outer housing mounted on the base and itsperipheral side walls define a chamber of a non-circular cross sectionand an open top through which whole milk or dried milk and water, orother constituents commonly used in preparing yogurt may be added to ayogurt starter, usually yogurt from the supermarket or a remanent of aprevious batch. One or more of either the peripheral side walls or thebase and/or the paddle member have embedded therein or otherwise supporta warming and heating element, such as a tungsten filament. A reversibleheat pump (thermoelectric heater/cooler) that is adapted to applywarming, and/or cooling, to the contents of the container may beemployed as well. A cover member is configured to fit atop theperipheral side walls of the outer container in covering relation to itsopen top. The cover member includes at least one electrical connectionwith the housing and at least one slip-ring electrical connection withthe rotating paddle or the center post. The outer housing has anintegrally molded, tubular center post which has a centrally locatedsleeve-bearing that is adapted to receive a paddle support shafttherethrough. The paddle support shaft has a retainer preventing it fromslipping downward. A rotating split paddle member is secured to itsupper end. The paddle blades are sufficiently long so that they extenddownwards into the yogurt or cheese mix placed in the container whenused.

Also disposed around the paddle support shaft in the base is a motor,detent magnet and reed switch magnet supporting means. This supportingmeans is releasibly secured to the base member by the detent, such thata predetermined force must be applied to the aforementioned supportingmeans before it is able to move in relation to the base member.

Finally, at least one drive motor with a gear reduction mechanism isaffixed to the supporting means for the rotatable motor, detent magnetand reed switch magnet for rotating the paddle support shaft and paddlerelative to the stationary housing to thereby periodically test thecontents in the chamber of the housing. The motor also rotates thesupporting means, detent magnet and reed switch magnet with respect tothe container upon the thickening of the contents in the container. Themotor is adapted to be driven either with predetermined duty cycles orcontinuously, dependent on the product being made.

The culturing container may have a double walled freezing bowl insertedinto it. The freezing bowl has a cylindrical, microwave heatablestainless steel interior wall and a non-cylindrical outer wall. Shiftingof the detent magnet and reed switch magnet supporting device alsotriggers a switch, shutting off the motor, timer and the warming elementand activating a cooling element.

In a sixth embodiment, the motor is disposed in the base and the detentis on the unit top. It has an insulated outer housing supported on abase, peripheral side walls defining a non-circular cross-section and anopen top through which whole milk, dried milk plus water or other yogurtconstituents are added to a yogurt starter, usually yogurt from thesupermarket or a remanent of a previous batch. Integrally molded withthe outer housing is a tubular center post. One or more of either theperipheral side walls or the base or the center post, and/or the paddlemember have embedded therein or otherwise support an electrical or otherwarming and/or heating element or reversible, thermoelectric heat pumpthat is adapted to apply warming or cooling, to the contents of thecontainer. A cover member is configured to rotate atop the peripheralside walls in covering relation to the open top of the container. Thecover member includes at least one vent hole (and at least one automaticstarter adding hole) formed therethrough, along with a centrally locatedhole that is adapted to receive a stub shaft on an occluder membertherethrough. The cover has rotating paddle blades secured thereto whichare sufficiently long so that they extend into the yogurt or cheese mixplaced in the container during use. Slip rings connect the center postelectrically with the cover. Also disposed about the occluder stub shaftand integral therewith is an occluding means for selectively coveringand opening the vent hole in the rotating cover member. The means forselectively occluding and opening the vent hole is again releasiblysecured to the cover member by a detent, such that a predeterminedretarding force must be applied to the paddle before the occluder isable to move independent of the cover member. Finally, at least onedrive motor with a gear reduction mechanism is affixed to the base forrotating the paddle support shaft within the tubular center post-sleeve.The motor is adapted to be driven either with predetermined duty cyclesor continuously, dependent on the product being made. Periodic rotationof the top and its attached paddle tests the consistency of the contentsin the container. As it thickens, the occluding means rotates away froma vent hole occluding position to an open position.

The culturing container may further contain or be replaced by a doublewalled freezing bowl having a cylindrical, microwave heatable stainlesssteel interior wall and a non cylindrical outer wall. Shifting of theoccluding device from the covering position to the open position alsotriggers a switch, shutting off the motor, timer and the warming elementand/or activating the cooling element. Alternatively, if the optionalvent cover is not utilized, cooling can rapidly occur with the devicedwelling in the refrigerator with its electrical cord extending out pastthe soft, door seal gasket.

When preparing yogurt, the machines of the present invention willpreferably be placed on the kitchen counter, but may also, in mostcases, be placed within the cooling compartment of a householdrefrigerator with the power cord for energizing the unit's motor andtiming and heating/cooling elements extending out the door to a walloutlet. A solid-state timer is included as a part of the appliance forperiodically energizing the motor(s) with a predetermined duty cyclewhereby at relatively long periodic intervals, e.g., about every 15minutes, the motor is energized for a relatively short time interval,e.g., about two seconds. This causes relative movement of the paddlewith respect to the non-circular container, resulting in the consistencyof the contents of the container being tested at infrequent intervals.As the incubation of the milk and yogurt starter continues in the warmedenvironment, a point will be reached where the mixture begins to rapidlygel. Under gelled conditions, the paddle and container will becomelocked against relative rotation and this results in the occluding meansrotating from a vent hole occluding position to a vent hole openposition. The rotation of the occluding means in the manner describedalso causes an electrical switch to open, shutting off power to themotor and to the warming element. With the power off and the vent holeopen, cool air from the refrigerator will quickly absorb the heat energywithin the appliance, terminating the culturing process. Alternatively,cooling can be achieved by having the switch reverse the polarity of thevoltage applied to a thermoelectric heat pump.

The yogurt and cheese making container is preferably designed to have anon-circular periphery around its open upper end and around its innerperipheral side walls so that the gelled and curdled products provide aresistant lock between the paddle and the container.

In the first embodiment described, the cover may also be placed atop thecontainer in any one of four positions. It has been found convenient toplace a plurality of electrical switch actuators atop the wall of thecontainer and surrounding the opening therein and then provide matingelectrical switch contacts on the cover member such that when the coveris placed on the container in a first of the four possible positions, itcauses the appliance to operate in a mode to produce yogurt. When thecover is rotated 90° and placed atop the container, only switches forcausing the appliance to operate in a mode for producing soft frozenyogurt or ice cream will be actuated. Similarly, another 90° rotation ofthe cover relative to the container will result in only those switchesfor causing the appliance to produce hard frozen yogurt or ice cream tobe actuated. The fourth possible position of the square cover relativeto the square base will cause only those switches to be actuated wherebythe appliance can be used to produce Ricotta cheese. Other alternativetypes of switching panels might be utilized. The cover and container ofa device utilizing the switching scheme just described are appropriatelycolor coded or otherwise marked to facilitate selection of a desiredoperating mode.

When the appliance of the first configuration of the present inventionis to be used in preparing frozen yogurt or ice cream, the cover isplaced on the container's open top in a different orientation such thatcooperating switch and switch actuating devices on the container andcover disconnect the heating element from its source of power. Apreviously chilled freezing bowl dimensioned to fit into the opening inthe container is removed from the refrigerator's freezer compartment andinserted into the opening of the container or inserted independently androtation is commenced. The previously prepared mix is then poured intothe freezing bowl, while the drive motor(s) are permitted tocontinuously drive either rotating paddle or container such that thefrozen yogurt mix forming on the cylindrical inner wall of the freezingbowl is continuously scraped therefrom. The relative rotation of thecontainer with respect to the paddle continues until the resistance onthe paddle due to the presence of the hard or soft frozen yogurtovercomes stronger predetermined retaining forces to again allow theoccluding means to rotate to the position wherein the electrical switchfor applying power to the motor is opened.

When the appliance of the present invention is to be used in makingagglutinated curd (Ricotta cheese), provision is made for the morenearly continuous rotation of the paddle in a warmed yogurt mix, stoppedonly about every 15 minutes for a shorter pause (about 5 minutes). Ayogurt culture, which is stirred relatively continuously, agglutinatesand forms a curd which, if subsequently not stirred, may settle as afirm mass sticking to the bottom of the irregular shaped container or,if stirred, may attach to and shrink on the stirring paddle, forming aball. When the paddle increasingly becomes mired in an agglutinatingmass which is attaching to the irregular shaped container, it causes aforce resisting movement of the paddle. When the paddle, with anattached curd-ball, abruptly re-accelerates from a stop to a turningmovement, the inertia of the curd ball on the paddle similarly causes atransient force sufficient to overcome the predetermined force betweenthe occluding means and the cover so that the device opens up the venthole in the cover and turns off the motor and timer and warming and/ormay reverse a heat pump.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of the first embodiment home yogurt/cheesemaking machine;

FIG. 2 is a partial cross-sectional view of the first embodimentapparatus of FIG. 1;

FIG. 3 is a vertical cross-sectional view of the second embodiment homeyogurt/cheese making machine of the present invention;

FIG. 4 is a cross-sectional view of the third embodiment homeyogurt/cheese making machine of the present invention;

FIG. 5 is a cross-sectional view of the fourth embodiment homeyogurt/cheese making machine of the present invention;

FIG. 6 is a cross-sectional view of the fifth embodiment homeyogurt/cheese making machine of the present invention;

FIG. 7 is a cross-sectional view of the sixth embodiment homeyogurt/cheese making machine of the present invention;

FIG. 8 is a schematic diagram of the electrical controls of the basicmachine when used only for preparing yogurt or cheese;

FIG. 9 is a schematic diagram of the electrical circuitry incorporatedin the machine for selectively preparing one of yogurt, hard and softfrozen yogurt or ice cream and cheese products;

FIG. 10 is a side elevational view of a yogurt "starter" addingattachment for the yogurt/cheese making machine; and

FIG. 11 is a top plan view of the attachment of FIG. 10.

DESCRIPTION OF THE FIRST EMBODIMENT

Referring first to FIG. 1, there is indicated generally by numeral 10 ahome appliance useful in preparing yogurt, soft or hard frozen yogurt orice cream, and cheese from a starter and either pre-heated bottled milkor a mixture of dried milk and water as well as other ingredients forproviding a desired taste and consistency. It is recognized that yogurtcan be prepared from nondairy products. Hence, the term "milk product"as used in the present application is intended to include both dairy andnon-dairy products from which yogurt can be produced. The machine isseen to comprise a base container 11 of generally square configurationdefined by a bottom 12 and four mutually perpendicular side walls 13,14, 15 and 16. The container 11 will preferably be molded from asuitable plastic and incorporated into the walls 13, 14, 15 and 16and/or the bottom 12 is a thermostatically controlled warming element17, here shown as an elongated coil or serpentine arrangement of anicrome wire that is arranged to warm the interior and, therefore, thecontents of the container. A reversible thermoelectric heat exchangerfor both warming and cooling might also be utilized. Other warming andheating element arrangements may be embedded in the paddle. Thethermostat control is identified by numeral 18 in the drawings. As usedherein "warming" is intended to mean raising or maintaining thetemperature of the milk product to a culturing temperature which may bebetween about 113° F. while "heating" involves bringing the milk productto about 203° F.

The four walls 13-16 define an open upper top 19 having downwardly andinwardly sloping edges as at 20 and 21. The mutually perpendicular sidewalls 13-16 and the bottom 12 are preferably formed of materials andinsulation so that the heat energy derived by passing electrical currentthrough the warming/heating element 17 will be inwardly directed. Theupper edges of the four side walls include a plurality of post-likeprotuberances, as at 22, which are spaced or otherwise distributed atpredetermined intervals and, as will be further explained, function aselectrical switch actuators.

Disposed above the base container 11 in the exploded view of FIG. 1 isan optional freezing bowl 23 that is used when preparing such productsas hard or soft frozen yogurt or ice cream. The freezing bowl, which isalso of a square outer shape, is dimensioned to be insertable into thebase container 11. The freezing bowl 23 has a substantially cylindricalinner wall 24, preferably formed from microwave heatable stainless steelor aluminum. The inner wall may have a non-stick coating, such asTeflon, thereby to facilitate release of frozen product therefrom.Disposed between the cylindrical inner wall 24 and the square outer walland nearly filling it is a chemical mixture exhibiting a low freezingpoint, a relatively high latent heat of fusion and a low coefficient ofexpansion. This material, when initially frozen, is capable of absorbingheat from the container contents over a reasonable period sufficient tocause the contents to freeze. The double-walled freezing bowl 23 has aninwardly and downwardly sloping surface 25 leading to the cylindricalchamber 24. Prior to use, the insert 23 is adapted to be placed in thefreezing compartment of a household refrigerator and chilled until thechemical material contained between the walls becomes frozen.

Sized to fit atop the rim of the base container 11 is a cover member 26,preferably fabricated from a suitable insulated plastic and having avent opening(s) 27, 28 and 29 formed through the thickness dimensionthereof. A further central opening 30 is also provided for receiving theshaft 31 of a motor-driven drive member 32 therethrough. The squarecover 26 further includes an additional opening 33 through which liquidingredients may be poured into the freezing bowl 23 when the cover is inplace thereon and the paddle is turning. The opening 33 is verticallyaligned with the sloped upper edges of the freezing bowl so that whenmaterial is poured through the opening 33, it will flow into thefreezing bowl. An integrally molded, upwardly projecting annular wall 34on cover 26 is designed to cooperate with the downwardly depending rimon drive member 32 to act as a baffle against inadvertent spillage whenpouring ingredients into opening 33. A snap-in, removable cap 35 is usedto seal the opening 33.

Positioned about the periphery of the cover 26 on the lower surfacethereof are a plurality of cavities comprising normally opened switchcontacts, as at 36, and which are positioned so as to cooperate with theswitch actuating pins 22 on the upper edge of the base of container 11.The switch contacts 36 may comprise conventional diaphragm-typeswitches, each comprising first and second layers of metallization thatare spaced apart from one another by an aperture insulating strip. Oneof the layers of metallization is deposited on a plastic (Mylar)membrane that when deformed through the aperture in the spacer layer,engages the second layer of metallization. Thus, when the cover 26 isassembled atop the base or container 11, only those diaphragm switches36 which are aligned with a switch actuator 22 will have their contactsclosed. The switch contacts are adapted to be connected, via printed orother wiring 37, to a control circuit 38 also mounted on the cover 26.Rather than utilizing diaphragm switches, the switch actuators 22themselves may be metal covered and function as a first electricalcontact designed to cooperate with second contacts formed in recesses onthe undersurface of the cover 26.

Disposed atop the cover 26 and loosely surrounding the shaft 31 of thedrive member 32 is an occluding member 39 having an integrally formedsleeve bearing 40 centrally disposed thereon. Washer-type spacers 41 and42 fit over shaft 31 on opposite ends of the sleeve bearing 40 toprevent frictional engagement between the occluder 39 and cover 26 anddrive member 32. A pair of electrical drive motors 43 and 44 are mountedon the occluding member 39. As best seen in the enlarged view of FIG. 2,the motor 43 and the motor 44 are slide mounted on the occluding member39 and have shafts 45 and 46, respectively, frictionally engaging anelastomeric band 47 deployed about an annular projection 48 that extendsdownwardly from the undersurface of the drive member 32.

Tension springs 49 and 50 are operatively coupled via the magnetic cores51 and 52 of the motors 43 and 44 as well as to the sleeve bearing 40 ofthe occluding member 39. The springs function to maintain the motorshafts 45 and 46 in firm engagement with the elastomeric friction band47 surrounding the annular projection 48 to inhibit slippage of themotor shafts on the friction band. A C-clip 53 holds the drive member,occluding member and cover together as a unit.

The paddle support shaft 31 is adapted to be coupled to a stub shaft 54on a paddle member 55. During use, the paddle is disposed within thecontainer 11 and adapted to be driven by the drive shaft 31 when themotors 43 and 44 are simultaneously energized. The machine of thepresent invention may also be constructed so that a warming/heatingelement may be contained in the paddle with slip-ring contacts forcoupling electrical power thereto.

The control circuit 38 disposed on the cover 26 is also wired to anelectromagnet 56 having first and second coils of differing numbers ofturns such that at least three different magnitudes of magneticattractive force can be applied for respectively causing a relativelymoderate magnetic attraction to a weak permanent magnet 57 on theoccluder 39 or, alternatively, two selectively greater attractiveforces. Reciprocally, the permanent magnet 57 can apply a weakattractive force to the core of the inactive electromagnet 56.

The occluding member 39 is arranged to shift between first and secondpositions. In the first position, the occluding member 39 blocks thevent holes 27, 28 and 29 and in its second position uncovers those holesto expose the contents of the machine within the container 11 to thecooling temperature of a refrigerator in which the machine may be placedduring use. When in the first position, a permanent magnet embedded inthe occluding member 39 and identified by numeral 58 cooperates with amagnetic reed switch 59 disposed on the cover 26 to maintain the reedswitch 59 closed. When the occluding member 39 is made to shift to itssecond position, the reed switch 59 is no longer under the influence ofthe permanent magnet 58 and its contacts open.

Referring now to the circuit diagram of FIG. 8, there is shown a circuitarrangement that may be used if the machine is only to be used in makingyogurt or cheese. A power cord 801 has its input prongs adapted to beconnected to a source of household current. A first insulated conductorin the power cord 802 connects to a first normally open contact 803 ofthe magnetic reed switch 804 (59 in FIG. 1) and its second contact 805is connected by a conductor 806 to a junction point 807 to which oneside of the warming/heating element 808 (17 in FIG. 1) is attached. Thesecond conductor of the power cord 812 is connected through terminalpoint 3 within the control module 813 to the remaining terminal of thewarming/heating element 808. The junction 807 is also connected toterminal point 2 within the controller module. The drive motors 809 and810 (43 and 44 in FIG. 1) are connected in parallel between theconductor 812 and a terminal point 1 in the controller module 813. A setof normally open timer operated contacts 811 are connected in seriesbetween terminal points 1 and 2. While mechanical switch contacts 811are depicted in the drawings, the controller 813 will typically be asolid state device that will be biased to either a conducting ornon-conducting state.

In use for preparing non-frozen yogurt, a yogurt starter and eitherpreviously heated bottled milk or dry, powdered milk plus warm water, ispoured into the container 11 and the upper assembly, including thepaddle 55, the occluding member 39, the drive member and the rectangularcover 26 are placed, as a unit, atop the container 11 and the drivemember 32 is manually rotated in the counterclockwise direction (whenviewed as in FIG. 1) by placing a finger in the recess 34 formed in theexposed upper surface of drive member 32 to thereby rotate the occludingmember to which it is effectively locked, to the occluding member'sinitial position blocking the vent openings 27, 28 and 29 formed throughthe cover 26. The assembly is then placed within a refrigerator with thepower cord 801 extending through the flexible rubber seal of therefrigerator door and then plugged into a wall outlet. With theoccluding member 39 in the position to occlude the openings 27, 28 and29, the permanent magnet 58 embedded in the occluder will cause thecontacts of the normally open reed switch 59 (804 in FIG. 8) to beclosed. As such, current will flow through the warming/heating element17 (808) to maintain the warmth of the milk/starter mix within thecontainer 11 at a desired culturing temperature. At this time, permanentmagnet 57 is attracted to the iron of the unenergized electromagnet 56(901 in FIG. 9) with a relatively weak force.

At relatively infrequent intervals, the timer control 813 will cause thecontacts 811 to close for a relatively short interval. Withoutlimitation, the contacts 811 may close about every 15 minutes for a timeinterval of about two seconds. When the contacts 811 close, anelectrical current is supplied not only to the warming/heating element17 (808), but also to the motors 43 and 44.

Upon energization of the motors 43 and 44, the drive member 32 will berotated in the counterclockwise direction to also rotate the paddle 55within the liquid mixture to thereby test the consistency of theconstituents. After a few hours, the yogurt mixture will convert from aliquid to a somewhat firm gel. This transition occurs relativelyrapidly.

Now, the next time that the timer contacts 811 are made to close, themotors 43 and 44 will attempt to rotate the drive member 32 and thepaddle 55 which are keyed to one another. Because of the square shape ofthe container 11, the paddle 55 will not only be unable to rotate withinthe gel but will also be unable to twirl the gelled yogurt and, as aresult, the motors affixed to the occluding member 39 will overcome therelatively weak magnetic force provided by magnet 57 and will cause theoccluding member 39 to rotate clockwise so as to uncover the ventopenings 27, 28 and 29 and simultaneously cause the contacts 803, 805 ofthe magnetic reed switch 59 to open. Opening of the contacts 803 and 805disconnects both the warming/heating element 17 and the controller/timer813 from the power source and thereby shuts off the motors 43 and 44 inFIG. 1.

Exposure of the gelled yogurt in the container 11 to the cool air withinthe refrigerator, via the vent openings 27, 28 and 29, will allow thecontents to cool rather rapidly, thereby terminating the warming processat a time when the consistency and flavor are optimum. Alternatively,the reversible thermoelectric heat exchanger is switched to coolingmode.

In making cheese, the controller is re-programmed so that the motors 43and 44 run more continuously and the warming element 17 is alsoenergized. Rather than continuous rotation, in the preferred mode forcheese making, the cycle allows about 15 minutes of rotation followed byabout 5 minutes of interruption--long enough for the curd to settle andbegin to agglutinate into a resistant mass. The cheese curd massinhibits rotation of the paddle 55. This causes the motors to now rotatethe occluding means, opening the reed switch 59 and disconnecting powerfrom the motors and warming element. The contacts 811 may open, forexample, about every 15 minutes for a time interval of about fiveminutes. When the paddle, either with its attached curd-ball or mired ina firm or semi-firm mass, reaccelerates, the inertial or resistanceforce is sufficient to overcome the predetermined weak force between theoccluding means and the cover so that the device opens up the venthole(s) in the cover and turns off the motor and the timer and theheating element.

The operation thus far described involves the making of regular yogurtand cheese. By configuring the circuit as in the diagram of FIG. 9,additional capability is provided to the apparatus of FIG. 1.Specifically, it can be used to prepare not only yogurt and cheese, butalso soft and hard frozen yogurt or ice cream.

When it is desired to make soft frozen yogurt, the optional insert 23 isutilized. The freezing bowl 23 will have been thoroughly chilled in afreezer or in the freezing compartment of the refrigerator before it isplaced into the base container 11. Rotation is started and previouslyprepared frozen yogurt mix is then poured into the cylindrical cavity ofthe freezing bowl 23, via access port 33 formed in the cover 26. Also,the cover 26 will have been installed on the base container 11 in adifferent orientation than when the machine is being used to createyogurt in the first instance. As will be explained, the repositioning ofthe cover 26 relative to the base container 11 will result in differentmodes of operation.

FIG. 9 is a schematic electrical diagram of the apparatus of the presentinvention when designed for additional or multiple use application. Inthis arrangement, the electromagnet 56 of FIG. 1 is represented by twocoils labeled T₁ and T₂ of electromagnet 901. The coils T₁ and T₂ areadapted to be connected between the conductor 903 of the AC supply linewhen switches 904 and 905 are closed. In addition, a bypass switch 906is provided which effectively removes the timer control 907 (38 inFIG. 1) from the circuit when it is closed.

The electromagnet 901 has fewer turns on coil T₁ than it does on coil T₂and, as a result, the electromagnet 901 provides a lesser restrainingforce to the occluder 39 when the switch 905 is closed than is affordedwhen switch 904 providing energization to the coil T₂, is closed.

It is to be further noted that a single pole, single throw normally openswitch 908 is connected in series with the warming element 909 (17 inFIG. 1) between terminal 3 of the timer control 907 and junction point910.

The open/closed state of the switches 904, 905, 906 and 908 isdetermined by the orientation of the cover 26 relative to the top of thecontainer 11. When making regular yogurt, the switch actuator pins 22will cooperate with the cover such that switch contacts 904, 905 and 906remain open while contact 908 is closed. However, when making soft,frozen yogurt, the cover will be positioned such that the switchactuators 22 will cooperate with the switches 904, 906 and 908 so thatcontacts of switch 904 will be closed, 905 will be open, 906 will beclosed and 908 will be open. As such, motors 911 and 912 (43 and 44 inFIG. 1) will operate continuously. With switch 908 open, no current willflow through the warming element 17. As the paddle is continuouslydriven within the cylindrical chamber 24 of the freezing bowl 23, whenthe yogurt freezes on the walls of the chamber 24, it will be scrapedoff by the continuously rotating paddle 55 and will be mixed with thestill somewhat liquid frozen yogurt mix remaining in the chamber. Ofcourse, it is also possible to provide the desired scraping action byrotating the container 11 relative to a stationary paddle disposed inthe cylindrical chamber, as in other embodiments yet to be described.

Once the consistency of the soft frozen yogurt becomes sufficientlystiff to overcome the attractive force due to current flowing throughthe coil T₁, the occluder 39 will again rotate due to the stalledcondition of the paddle 55. The occluder will again reposition so as toopen the reed switch contacts 913 and 914 to disconnect the motors 911and 912 and to remove current from the coil T₁. While not shown, it isalso contemplated that the machine of the present invention be providedwith an audible signaling device which would sound so that the softfrozen yogurt can be removed from the freezing bowl 23 before the yogurtbecomes more firm due to the freezing action of the insert. Freezing ofsoft frozen yogurt to the inner wall of the bowl while attemptingremoval of the product can be countered by placing the bowl with itsmicrowave-heatable, smooth-contoured, stainless-steel inner cylinder ina microwave oven and heating it briefly. A Teflon® lining might also beutilized.

When the machine of the present invention is to be used to produce hardfrozen yogurt or ice cream, the freezing bowl 23 is again used, but thecover will now be repositioned on the base container 11 such that theswitch actuators 22 cooperate with the switches 36 on the cover 26 tocause switches 905 and 906 to be closed and switches 904 and 908 to beopen, or switches 904 and 905 may both be closed. Also, the machine ofthe present invention may be inserted into the refrigerator's freezercompartment and the vent cover removed to permit access by ambient air.Given the fact that the coil T₂ of the electromagnet 901 (56 in FIG. 1)has a greater number of turns than the coil T₁ which is active in makingsoft frozen yogurt, the cover 26 and the occluder 39 will be attractedto one another with an increased force. With switch 908 open, theheating element 909 is not energized. Also, because switch 906 isclosed, the timer circuit 907 is no longer functional and the motors 43and 44 will run continuously, until such time as the magnetic reedswitch 914 opens. As heat energy is removed from the yogurt mixturewithin the cylindrical compartment 24 of the freezing bowl 23 by thechemical contained between the walls of the insert and by the action ofthe refrigerator's freezing compartment, the yogurt will become more andmore firm until a point is reached wherein the scraper paddle 55, inattempting to scrape and stir the freezing yogurt, will overcome theforce exerted by the coil T₂ of the electromagnet and the motors willthen drive the occluding means 39 on which they are mounted so as tocause the magnetic reed switch contacts 913 and 914 to open and therebydisconnect the motors and the coil T₂ from the power lines.

Again, removal of the frozen product from the bowl 23 may be facilitatedby briefly placing the freezing bowl with its microwave heatable innercylinder and its frozen contents into a microwave oven and heating itfor a short time sufficient to melt the bond of the yogurt to the wallof the bowl. If, after the hard frozen process has completed, the devicehas remained in the freezing compartment of the refrigerator and a hardblock with the paddle frozen in has resulted, then the heating coils inthe paddle can be activated to facilitate its extraction.

When the machine of the present invention is to be used in makingRicotta cheese, the freezing bowl is not used and the motors 43 and 44run with a duty cycle in which they remain on for a relatively longinterval and off for a somewhat shorter interval. The warming elementwill remain energized and the weak magnet 57 will provide the attractiveforce between the cover 26 and the occluding member 39. Statedotherwise, the cover 26 will be positioned on the container such thatthe switch actuators 22 on the container will cooperate with theswitches 36 to cause switch 904 to be open, 905 to be open, 906 to beopen, and 908 to be closed. The milk and starter will be placed in thecontainer 11 and the occluding member positioned so as to occlude theopenings 27, 28 and 29 in the cover and to cause the magnetic reedswitch contacts 913 and 914 to be closed. Because the mixture is beingwarmed, and largely, if not continuously stirred by the paddle overprolonged periods of time, a point will be reached wherein the mixturebegins to flocculate and curdle and it may agglutinate into a ratherfirm mass on the bottom of the container if stirring ceases for a time.Also, some mixtures may tend to aggregate and form a curd ball on thepaddle itself. When this process is complete to the point where the massof the curd ball adds sufficient inertia to inhibit rotation of thepaddle or an attempt to restart the paddle movement following aninterruption in its rotation by opening of the timer switch 915 (811 inFIG. 8), the attractive force afforded by the permanent magnet 57 willbe overcome and will result in the occluding member 39 shifting inposition, due to the action of the motors, to the point where themagnetic reed switch 916 (804 in FIG. 8) again opens to therebydisconnect the heating element 909 and the motors 911 and 912 from thepower source.

Rather than using a friction drive between the motor shafts and theelastomeric band on the drive member, an arrangement of gears driven bya single motor may be used instead.

Further, and as is mentioned in the foregoing specification, a heating(and warming) element may be located in the paddle member rather than inthe walls of the container 11. This would afford the additionaladvantage of allowing the paddle to be extracted from hard frozen yogurtor ice cream by heating the paddle for a short interval to melt the icecream at its interface with the paddle. Any of a variety of electricalslip ring contacts can be used to provide electrical energy to a heatingelement in a rotating member. Another modification would be to sensechanges in the current drawn by the motors as the consistency of theproduct varies from a liquid to a gel or to a solid and to use thatsensed current change to shut off the current to the warming element andto the drive motor(s) and to switch on cooling by the reversiblethermoelectric warmer/cooler. A safety switch may also be incorporatedwhich would shut down all possibility of current flow whenever the coveris removed. A reduced voltage may be utilized for all functions to avoidelectrical shock to the user. It is also contemplated that the applianceof the present invention can be modified to permit bread making andother food processing in addition to the functions described herein.

Description of the Second Embodiment

Referring first to FIG. 3, there is indicated generally by numeral 310 asecond embodiment of a home appliance useful in preparing yogurt, softor hard frozen yogurt or ice cream, and cheese from a starter and eitherheated bottled milk or a mixture of dried milk and tap water. Themachine is seen to comprise a culturing container 311 of generallynon-circular (square or with baffles) configuration defined by a bottom303 and mutually perpendicular side walls 304 and 305. The container 311will preferably be molded or shaped from a suitable plastic or metal.The four walls, as at 304 and 305, define an open upper top 306 ofnon-cylindrical configuration. The bottom of the container is adaptedcentrally to be splined to a stub shaft 307 and is thereby able to bedriven by the shaft of the motor 308 when it is energized.

Shown within container 311 is an optional freezing bowl 323 that is usedwhen preparing such products as hard or soft frozen yogurt or ice cream.The freezing bowl 323, which is also of a non-cylindrical outer shape,is dimensioned to be insertable into the container 311. The freezingbowl 323 has a substantially cylindrical inner wall 324, preferablyformed from microwave heatable stainless steel or aluminum. Disposedbetween the cylindrical inner wall 324 and the non-cylindrical outerwall and nearly filling it is a chemical mixture exhibiting a relativelyhigh latent heat of fusion and a low coefficient of expansion uponchanging from a liquid to a solid state. Prior to use, the insert 323 isadapted to be placed in the freezing compartment of a householdrefrigerator and chilled until the chemical material contained betweenthe walls becomes frozen.

The stationary insulated housing 309, which is fastened to thestationary base 312, is also locked removably to a stationary paddlesupporting rim 313, which in turn is roofed by the stationary removablecover 314.

Sized to fit atop the opening rim of the housing and non-rotatably andelectrically keyed to it is a paddle 315, disposed within the mix in thecontainer or freezing bowl. The machine of the present invention mayalso be constructed so that the stationary paddle 315 contains athermostatically controlled electrical heating/warming element, hereshown as a serpentine arrangement of nicrome wire 316.

The insulated cover member 314 is sized to fit atop the rim of thepaddle support member and the container. It is preferably manufacturedfrom a suitable plastic. When the cover is removed, liquid ingredientscan be poured into the freezing bowl even while the paddle remains inplace and the bowl is rotating. Also the cover is adapted to support aninsulated, solenoid-valved container for liquid yogurt or cheese starterwhich may be utilized to automatically add starter subsequent to thepre-heating and cooling steps when unheated bottled milk is utilized.There are electrical connections at 317 and 318 between the housing andpaddle and cover to facilitate plugging in the unit for timed deliveryof a starter through the cover opening 319 when plug 320 is removed.

The insulated base 312 has at least one vent opening 321 formed throughthe thickness dimension thereof, with a removable vent cover 322. Afurther centrally disposed sleeve bearing is provided therethrough forreceiving the stub shaft 307 of the motor drive member 308 therethrough.The stub shaft can be keyed to the container and/or the freezing bowlwhich are designed to be driven by the stub shaft.

Disposed in the base 312 and loosely surrounding the shaft 307 of thedrive member is a rotatable occluding member 324 having an integrallyformed sleeve bearing centrally disposed. The electrical motor with gearreduction 308 is fixed to the underside of the occluding member 324 andis arranged to rotate the container relative to the stationary paddle315, housing 309 and base 312. A thermostatically controlled reversibleheat exchanger 325 is also mounted within the base 312. Both internal326 (within the housing) and external 327 (outside the insulation) fansare mounted in relation to the reversible heat exchanger. The heatexchanger is preferably a reversible polarity thermoelectric devicecapable of both heating and cooling. The appropriate switches areadapted to be connected, via printed or other wiring, to a controlcircuit also mounted on (in) the base. A drain hole as at 328 providesegress for any spillage of liquid occurring within the housing.

The occluding member 324 is arranged to shift between first and secondpositions. In the first position, the occluding member blocks the ventopening 321 and in its second position uncovers the same to expose thecontents of the machine within the container 311 to the cooling air of arefrigerator in which the machine may be placed during use, assuming thevent cover 322 is removed. The reversible heat pump 325 may also beswitched to the cooling mode, in which case the vent cover remains inplace.

When in the first position, a permanent magnet 330 embedded in theoccluding member 324 cooperates with a magnetic reed switch 329 disposedon the base 312 to maintain the reed switch 329 closed. When theoccluding member 324 is made to shift to its second position, the reedswitch 329 is no longer under the influence of the permanent magnet 330and its contacts open.

A timing control circuit like that earlier described is disposed in thebase 312 and is wired to an electromagnet 331 having first and secondcoils of differing numbers of turns, such that as many as threedifferent magnitudes of magnetic attractive force can be applied,respectively causing a relatively moderate magnetic attraction to a weakpermanent magnet 332 on the occluder 324 or, alternatively, one or twoselectively greater attractive forces. Reciprocally, the weak permanentmagnet 332 can apply a weak attractive force to the core of the inactiveelectromagnet 331.

A circuit like that depicted in the diagram of FIG. 8 may be used withthe embodiment of FIG. 3 if the machine is only to be used in makingyogurt or cheese.

In use for preparing non-frozen yogurt, a yogurt starter and eitherpreviously heated liquid milk or dry, powdered milk plus water, ispoured into the container 311 and the cover 314 is placed on top.(Alternatively, non-heated milk can be utilized and heating and coolingand starter adding can be carried out automatically by the device priorto the machine's automatically proceeding on with the followingoperations). The occluding member in the base (occluder and motor andpermanent magnets) is manually rotated in the clockwise direction (whenviewed from above) by placing a finger against the tab 333 protrudingthrough the base from the occluding member to thereby rotate theoccluding member to its initial position blocking the vent openings 321.Without the vent cover, the assembly may then be placed within arefrigerator with the power cord extending through the soft,compressible gasket of the refrigerator door and plugged into a walloutlet. Alternatively, the device may be placed on the counter top, theelectrical cord plugged in and, with the vent cover in place, thereversible heat exchanger permitted to function consecutively in bothits warming and cooling modes. With the occluding member 324 in theposition to occlude the opening 321, the permanent magnet 330 embeddedin the occluder will cause the contacts of the normally open reed switch329 to be closed. As such, current will flow through the warming element325 and/or 316 in the paddle to warm the milk and starter mix within thecontainer 311. At this time, permanent magnet 332 is attracted to theiron of the unenergized electromagnet 331 with a relatively weak force.

At relatively infrequent intervals, the timer control will cause thecontacts 811 to also close for a comparatively short interval. Withoutlimitation, the contacts 811 may close about every 15 minutes for a timeinterval of about two seconds. When the contacts 811 close, anelectrical current is supplied not only to the warmer 316 and/or 325,but also to the motor 308. Upon energization of the motor 308, andassuming a stationary paddle 315, the shaft and stub shaft 307 will berotated in the clockwise direction to also rotate the container 311around the liquid mixture to thereby test the consistency of theconstituents. After a few hours, the yogurt mixture will convert from aliquid to a somewhat firm gel. This transition occurs relativelyrapidly.

Now, the next time that the timer contacts 811 are made to close, themotor will attempt to rotate the stub shaft 307 and the container whichare keyed to one another. Because of the rectangular shape of thecontainer 311, the container will not be able to rotate around the geland will also be unable to swirl the gelled yogurt and, as a result, themotor 308 affixed to the occluding member 324 will overcome therelatively weak magnetic force provided by the magnet and will cause theoccluder to rotate counterclockwise so as to uncover the vent opening321, and simultaneously cause the contacts of the magnetic reed switch329 to open. Opening of the contacts disconnects both the heatingelement and the timer from the power source and shuts off the motor 308,all as previously explained.

Exposure of the gelled yogurt in the container 311 to the cool airwithin the refrigerator, via the vent opening will allow the contents tocool rather rapidly, thereby terminating the incubation process at atime when the consistency and flavor are optimum. Alternatively, thepolarity to the thermoelectric heated/cooler 325 may be reversed,similarly commencing cooling.

In making cheese, the controller time-ratio switch is adjusted and themotor 308 is made to run intermittently for approximately fifteenminutes and permitted to rest for approximately five minutes. After aperiod of time, the milk and starter mix will curdle and fall to thebottom of the container and agglutinate and become a solid mass. At thispoint, the cheese mass will inhibit rotation of the container inrelation to the paddle 315. This causes the motor to now rotate theoccluding member, opening the reed switch and disconnecting power fromthe motor and warming element and either opening up the vent if it isnot further covered or switching on the cooling mode.

The operation thus far described involves the making of regular yogurtand cheese. By configuring the circuit as in the diagram of FIG. 9,additional capability is provided to the apparatus of FIG. 3.Specifically, it can be used to prepare not only yogurt and cheese, butalso soft and hard frozen yogurt or ice cream in the same manner asearlier explained.

When it is desired to make soft frozen yogurt, the optional insert 323is utilized. The freezing bowl 323 will have been thoroughly frozen in afreezer or in the freezing compartment of the refrigerator before it isplaced into the container 311. After rotation has been started,previously prepared frozen yogurt mix is poured into the cylindricalcavity of the quick freeze insert 323, via the hole 319 in cover 314 orwith the cover removed.

Once the consistency of the soft frozen yogurt becomes sufficientlystiff to overcome the attractive force due to current flowing throughthe coil T₁ of the electromagnet 901, the occluder 323 will again rotatedue to the stalled condition of the bowl in relation to the paddle 315.The occluder will again reposition so as to open the reed switchcontacts 913 and 914 to disconnect the motor 308 and to remove currentfrom the coil T₁. While not shown, it is also contemplated that themachine of the present invention be provided with an audible signalingdevice which would sound so that the soft frozen yogurt can be removedfrom the freezing bowl 324 before the yogurt adheres to it due to thefreezing action of the insert.

Also, while making hard frozen yogurt or ice cream, the machine of thepresent invention may be inserted into the refrigerator's freezercompartment. Given the fact that the coil T₂ of the electromagnet 901has a greater number of turns than the coil T₁ which is active in makingsoft frozen yogurt, the electromagnet and the occluder magnet will beattracted to one another with an increased force. With switch 908 open,the warming element 909 (316 in FIG. 3) is not energized. Also, becauseswitch 906 is closed, the timer circuit is no longer functional and themotor 308 will run continuously until such time as the magnetic reedswitch 329 opens. As heat energy is removed from the yogurt mixturewithin the cylindrical compartment of the freezing bowl 323 by thechemical contained between the walls of the insert and by the action ofthe refrigerator's freezing compartment, the yogurt will become more andmore firm until a point is reached wherein the scraper paddle 315, inattempting to scrape and stir the freezing yogurt, will overcome theforce exerted by the coil T₂ of the electromagnet and the motor willthen drive the occluding means 324 on which it is mounted so as to causethe magnetic reed switch contacts to open and thereby disconnect themotor and the coil T₂ from the power lines. Electrical resistanceheating of the paddle and microwave heating of the inner wall of thefreezing bowl may aid the process of removing hard frozen yogurt thathas been neglected for some period of time from the freezing bowl.

When the machine of the embodiment of FIG. 3 is to be used in makingRicotta cheese, the freezing bowl is not used and, as earlier explained,the motor is run more continuously with a duty cycle in which it remainson for a relatively long interval and off for a somewhat shorterinterval. The warming element will remain energized and the weak magnetwill provide the attractive force between the base 312 and the occludingmeans 324. The milk and starter will be placed in the container 311 andthe occluder positioned so as to occlude the opening 321 in the base andto cause the magnetic reed switch 329 to be closed. Because the mixtureis being warmed and stirred by the stationary paddle in the irregularshaped rotating container over prolonged periods of time, a point willbe reached wherein curd forms and gravitates to the bottom of the mixduring non-stirring intervals and begins to agglutinate and form into arather firm mass on the bottom of the container. When the process iscomplete to the point where this mass inhibits rotation, the increasedresistance will be enough to overcome the attractive force afforded bythe permanent magnet 332 and will result in the occluding means 324shifting in position due to the action of the motor to the point wherethe magnetic reed switch 329 again opens to thereby disconnect theheating element 316 and the motor 308 from the household power source.

A modification would be to sense changes in the current drawn by themotor as the consistency of the product varies from a liquid to a gel ora solid and to use that sensed current change to control the movement ofthe occluding means and/or to shut off the current to the heatingelement and/or to the drive motor(s). A safety switch might beincorporated which would shut down all possibility of current flowwhenever the cover is removed and, also, a reduced voltage might beutilized for all functions to avoid electrical shock to the user. It isalso contemplated that the appliance of the present invention might befurther modified to permit bread making and other rotation based foodprocessing in addition to the functions described herein.

Description of the Third Embodiment

A third preferred embodiment of the invention is illustrated in thecross-sectional view of FIG. 4. It is similar in many respects to thepreviously described first and second embodiments, but differs therefromprimarily in the fact that the drive motor for a rotating paddle isdisposed on the unit's cover member while the occluding device islocated in the unit's base.

Referring to FIG. 4, there is indicated generally by numeral 401 a homeappliance useful in the preparation of yogurt, soft frozen yogurt, hardfrozen yogurt and Ricotta cheese. It comprises an outer, molded plastichousing 402 having an outer wall 403 and an inner wall 404 spaced fromthe outer wall, leaving an insulating air chamber 405. The housingincludes a base 406 that, as in the earlier embodiments, includes atimer and control circuit like that illustrated in FIGS. 8 and 9.

Insertable within the housing 402 is a container 407. The container 407is designed to have a non-circular cross-section. As in the earlierembodiments, the container 407 will typically hold the milk during thepreparation of regular soft yogurt, but optionally, may receive afreezing bowl 408 therein. The freezing bowl 408 is a double-walledstructure having a freezing liquid 409 contained between the walls. Thefreezing bowl is, again, used when it is desired to prepare soft frozenor hard frozen yogurt using the machine of the present invention.

A top member 410 is adapted to fit on the housing 402 in coveringrelation to its open top. The cover 410 includes a central aperture 411containing a sleeve bearing 412 which journals a shaft 413 of anelectric motor 414. The shaft 413 is designed to mate with a stem 415 ofa rotatable paddle 416. The width of the paddle is designed to closelyconform to the inner wall of the freezing bowl.

In order to deliver electrical power to the motor 414, an electricalconductor 417 connected to a motor terminal at one end also connects toan electrical contact 418 on the cover 410 and a mating contact on thehousing 402. A further conductor, not shown, traverses through thehousing wall into the base 406 for connection to the control circuitcontained therein, like that shown at 38 in FIG. 1, but not specificallyillustrated in FIG. 4.

The cover also is molded so as to include voids as at 419 and 420 whichimproves the thermal insulating properties of the cover. Also formed inthe cover 410 is a circular opening 421 adapted to be sealed by aremovable plug 422. With the plug removed, it is possible to pouringredients through the opening 421 into the container 407 or thefreezing bowl 408 as the case may be.

Further conductors, as at 423, connect between power contacts 424 on thecover and housing for applying power to a protected electrical socket425 on the cover 410. This socket is adapted to receive a yogurt starterintroducer device in FIGS. 10 and 11 having a solenoid actuated shutterwhich is made to open by the timed delivery of a control signal from thecontrol circuit to the solenoid, via contacts 424 and 425 and theconductors 423 connecting them. With the shutter open, the contents ofthe starter adding device flow into the container 407 at an appropriatetime in the cycle, all as will be further explained hereinbelow.

With continued reference to FIG. 4, it can be seen that there is formedin the base a passageway 426 through which cool air may flow when theremovable plug 427 is absent. This plug is not used when the yogurtmaking appliance of the present invention is to be used in combinationwith a household refrigerator. Placement of the unit 401 in a householdrefrigerator would then permit cool air to flow through the apertures428 in the base and through the aperture 426 to circulate in the space429 between the inner wall 404 of the housing and the adjacent wall ofthe container 407.

By providing a thermoelectric heat exchanger, as at 433, it can assistin both the heating and cooling functions employed in the yogurt makingprocess. The thermoelectric device 433, is of a well known type wherewhen a voltage of first polarity is applied the unit will provide aheating function and when the polarity is reversed, cooling takes place.In addition to the heating that may be provided by the thermoelectricunit 433, the paddle 416 includes a heating element 434 therein which isadapted to be energized by way of slip rings 435. In that the paddle 416remains in intimate contact with the yogurt constituents, the warmthgiven off thereby aids in the culturing process.

As in the earlier embodiments, there is shown cooperating with the ventopening 426 in the base, an occluder member 436 that extends through aradial slot 437 formed in the base 406. It is fixedly attached to aturntable shaft 438 that passes upward through the base and connects toan extendable splined drum 439 that mates with a recessed area 440formed in the bottom of the container 407 or the freezing bowl 409.Thus, rotation of the container 407 will also result in rotation of theoccluder member 436.

A detent in the form of an electromagnet 441, as before, cooperates witha permanent magnet 442 attached to the occluder member 436 for applyinga predetermined force resisting rotation of the occluder member and,accordingly, rotation of the container 407 by virtue of the connectionafforded by the shaft 438 and the spline drum 439 connecting the two.

The base further incorporates a magnetic reed switch 444 therein havingcontacts that are under the influence of a permanent magnet 443 mountedin the occluder member when the occluder member 436 is in a firstorientation where the passageway 426 is being occluded. An extension 445of the occluder protrudes laterally through the side wall of the base sothat it is accessible for manually setting the device in itsvent-covered starting mode.

In that the control circuit depicted in FIGS. 8 and 9 has already beenexplained in connection with preceding embodiments, no furtherexplanation and mode of operation is deemed to be necessary for anunderstanding of the construction and operation of the embodiment ofFIG. 4.

In use, with the occluder 436 initially set in its starting position andwith the freezing bowl 409 removed, pre-heated bottled milk or a mixtureof warm water and dried milk may be added into the container 407 throughthe opening 421 in the cover. At this point, the power plug may beconnected to a source of household current for initially energizing thefilament 434 in the paddle 416 as well as the thermoelectricheater/cooler 433 mounted in the unit's base. The combination or eitherof these two heat sources causes the ingredients to be warmed. Atperiodic intervals determined by the timer used in the control circuit,the motor 414 will be energized to rotate the paddle momentarily so asto "test" the consistency of the contents of the container. Stated asbefore, motor 414 may be energized for about two seconds every fifteenminutes for this purpose. When the point is reached where theingredients begin to gel, because of the non-circular cross-sectionalprofile of the container 407, the paddle will become somewhat bonded tothe container to the point where the container itself will begin torotate with the paddle and thereby rotate the occluder member 436against the magnetic force provided by the magnet 441 comprising thedetent member. The occluder member thus will swing to a position nolonger occluding the vent hole 426. Movement of the occluder 436 alsoincreases the separation between the reed switch 444 and its cooperatingpermanent magnet 443, allowing the switch contacts of the reed switch toreverse, shutting off the motor and disconnecting the heating elementfrom the power source.

Assuming that the unit has been placed in a refrigerator, cooling aircan now propagate through ports 428 and through the vent 426 and up andaround the container to terminate the culturing process at an optimumpoint.

If it is assumed that the device includes the thermoelectric unit 433,it would not be necessary to place the yogurt maker within arefrigerator. Here, movement of the occluder so as to cause the reedswitch contacts to reverse may be used not only to shut off the motor414, but also to reverse the polarity of the voltage applied to thethermoelectric unit from its heating mode to its cooling mode. The wayin which soft frozen yogurt, hard frozen yogurt and Ricotta cheese canbe made using the present invention applies equally to the embodiment ofFIG. 4 and, hence, it is deemed unnecessary to repeat that explanation.

Description of the Fourth Embodiment

Referring first to FIG. 5, there is indicated generally by numeral 501 afurther embodiment of a home appliance useful in preparing yogurt, softor hard frozen yogurt or ice cream, and cheese from a starter and eitherbottled milk or a mixture of dried, powdered milk and water. As in thepreviously described embodiments, the machine is seen to comprise arotatable container 502 of generally square or baffled irregular,non-cylindrical construction defined by a bottom 503 and mutuallyperpendicular side walls as at 504 and 505. The container 502 willpreferably be molded or formed from a suitable plastic or metal. Thebottom 503 is keyed centrally at 506 to mate with a stub drive shaft 507having a splined hub 508 thereon. The four walls of container 502 definean open upper top 509.

Displayed within the container is an optional freezing bowl, indicatedgenerally by numeral 510, that is used when preparing hard or softfrozen yogurt or ice cream. The freezing bowl is identical inconstruction to what has earlier been described and need not beexplained further.

Surrounding the container 502 and/or the optional freezing bowl 510 isan insulated housing 511 composed of a base 512, enclosure 513 and cover514. The insulated base contains a motor 515 with the stub drive shaft507 that is keyed to interact with and support the container 502, or thefreezing bowl 510. The motor is underneath the base and there is abearing (not shown) for the shaft to pass through to the top of the base512. There is also a drain duct 516 through the base. A thermoelectricheat exchanger 517 with a drip guard cover 518 is disposed in an airvent 519 that is formed in the top of the base 512. An air circulationpath between the inside of the enclosure 513 and the outer wall of thecontainer 502 is in fluid communication with air vent 519 allowing forthe passage of warming and cooling air from the thermoelectric heatexchanger to act on the container 502.

The insulating cover member 514 is preferably fabricated from a suitableplastic and it has an opening 530 through the thickness dimensionthereof. The cover further includes an additional opening through whichliquid ingredients can be poured into the freezing bowl while thefreezing bowl is rotating and the cover is in place thereon. The coverfurthermore includes an integrally formed sleeve bearing 521 centrallydisposed therethrough for receiving the shaft 522 of a paddle 523. Theinsulated cover furthermore supports an electromagnet 524 and a reedswitch 525.

An occluding member 526 sits atop the cover, with two permanent magnets527 and 528 embedded in and attached to its periphery for interactionwith the reed switch 525 and the core of the detent electromagnet 524,respectively. The occluding member is integral with the paddle supportshaft 522. During use, the paddle 523 is disposed within the containerin a stationary, but potentially rotatable mode. The machine of thepresent invention may be constructed so that a warming-heating elementas at 529 can be contained in the paddle, as well as or rather thanhaving a thermoelectric heat exchanger 517 in the base.

A control circuit like that of FIG. 8 is disposed on the cover or in thebase 512. It is also wired to the electromagnet having a pair of coilsof differing numbers of turns such that two different magnitudes ofmagnetic attractive force can be applied for respectively causing arelatively moderate magnetic attraction to the weak permanent magnet 528on the occluding member 526 or, alternatively, a greater attractiveforce.

The occluding member 526 is arranged to shift between first and secondpositions. In the first position, it blocks the vent hole 530 and in itssecond position uncovers this hole to expose the contents of the machinewithin the housing 511 to the cooling temperature of a refrigerator inwhich the machine may be placed during use. When in the first position,the permanent magnet 527 embedded in the occluding member cooperateswith the magnetic reed switch 525 disposed on the cover to maintain thereed switch closed. When the occluder is made to shift to its secondposition, the reed switch is no longer under the influence of thepermanent magnet and its contacts open.

From what has been described in explaining the operation of theembodiments of FIGS. 1 through 4, the reader will clearly understand howthe present embodiment functions in preparing yogurt, frozen yogurt andRicotta cheese.

Upon energization of the motor 515, the container 502 will be rotated inthe clockwise direction to also relatively rotate the paddle within theliquid mixture to thereby test the consistency of the constituents.After a few hours, the yogurt mixture will convert from a liquid to asomewhat firm gel. This transition occurs relatively rapidly.

Now, the next time that the timer contacts are made to close, the motorwill attempt to rotate the container. It will be impossible for thecontainer to swirl a gel around the paddle and because of the irregularshape of the container and the shape of the paddle, the container andpaddle will in effect be locked together. As a result, the motor beingkeyed to the container will overcome the relatively weak magnetic forceprovided by magnet 528 and will cause the paddle and occluder to rotateso as to uncover the vent opening 530 and simultaneously cause thecontacts of the magnetic reed switch 525 to open. Opening of thecontacts disconnects both the warming element and the controller/timerfrom the power source and thereby shuts off the motor.

Exposure of the gelled yogurt in the container 502 to the cool airwithin the refrigerator, via the now open vent will allow the contentsto cool rather rapidly, thereby terminating the incubation process at atime when the consistency and flavor are optimum.

Description of the Fifth Embodiment

Referring next to FIG. 6, there is shown a fifth embodiment of theinvention. It resembles the second embodiment (FIG. 3) in that the drivemotor and occluder are disposed in the base. However, it differstherefrom in the manner in which relative motion is created between thecontainer and the paddle. In the embodiment of FIG. 3, the container isadapted to be rotated by the motor, whereas in the embodiment of FIG. 6,the container remains stationary and it is the paddle that is themotor-driven member.

In implementing the yogurt maker of FIG. 6, the outer molded plastichousing 601 has an integrally formed, centrally disposed tubular centerpost 602 projecting upwardly from the housing base 603. Contained withinthe central bore of the tubular center post 602 is a drive shaft 604that is adapted to be driven by the motor/gear reduction device 605located in the base portion 606 of the outer housing 601. Affixed to theshaft 604 proximate its upper end is a split paddle 607, which, duringuse, fits within the chamber defined by the inner wall 608 of thehousing 601 or within a specially formed freezing bowl 609 in thoseinstances where the machine is being used to prepare soft or hard frozenyogurt.

The freezing bowl 609 has an outer wall 610 and an inner wall 611 thatare spaced apart from one another, allowing a freezable liquid 612 to betrapped there between. The inner and outer walls 610 and 611 abut oneanother in the center of the freezing bowl and form an upwardlyextending tubular projection 613 whose inside diameter is slightlygreater than the outside diameter of the molded plastic center post 602.As such, the freezing bowl 609 can be inserted into the chamber definedby the outer housing by slipping the freezing bowl over the center post602.

A cover 614 is designed to fit onto the open upper end of the housing601 in covering relation thereto. Voids, as at 615 and 616, are formedin the top to add to its insulating qualities. An opening is formedthrough the top 614 at 617, allowing ingredients to be poured into thecontainer or freezing bowl as the machine is operating. A cap or plug618 can be used to seal the opening 617.

The top 614 also includes a bearing 619 into which the upper end of theshaft 604 is fitted. Furthermore, electrical slip rings 620 and 621mounted in the cover and in the paddle, respectively, permit anelectrical current to flow from a conductor 622 disposed within thecover to a heating element (not shown) disposed within the paddle 607.Also not visible in the embodiment of FIG. 6 are conductors leading fromthe power cord through the housing 601 to mating contacts 623 and 624between the cover 614 and the upper rim of the housing 601. Again, inFIG. 6, provision is made for positioning a yogurt starter adder deviceatop the cover 614. Specifically, and as earlier described, the adderdevice includes a solenoid actuated shutter at the base of an insulatedfunnel which can fit through the opening 617 when the plug 618 isremoved. An electrical connection to the solenoid is provided viacontact 624, conductor 625 and socket 626 into which contacts on thestarter adder device are insertable.

The motor 605 is shown as being affixed to an occluder member 627 and ithas a handle portion 628 extending out through a slot 629 formed in thebase 606 of the housing. Mounted on the occluder 627 is a permanentmagnet 629 adapted to cooperate with a magnetic reed switch 630 affixedto the housing closely adjacent the reed switch when the occluder is ina first position. The occluder also supports a permanent magnet 631positioned to cooperate with a pair of coils of an electromagnet 632.The control circuit for the embodiment of FIG. 6 is the same as for theprevious embodiments and is shown in detail in FIGS. 8 and 9. In thatthe construction and mode of operation of that control circuit hasalready been explained in conjunction with the description of theearlier embodiments, it is deemed unnecessary to repeat thatdescription. Suffice it to say, that when the machine is first turnedon, the yogurt mix is maintained warm by the resistance element disposedin the paddle 607 and/or by a thermoelectric heat exchanger 633 shownmounted in the side wall of the housing 601. Periodically, the timerportion of the control circuit closes contacts for energizing the motor605 to thereby "test" the consistency of the yogurt mix as culturingtakes place. When the point is reached in the culturing process wherethe yogurt begins to gel, a resistance is imparted to the paddle 607causing the paddle to stall but with the motor 605 continuing to run,the occluder pivots from its home position to a position which breaksthe magnetic attraction between the reed switch 630 and the permanentmagnet 629 to thereby disconnect the motor and timer from the electricalsupply and reversing the polarity of the voltage applied to thethermoelectric unit causing it to cool rather than warm.

Description of the Sixth Embodiment

Comparing the yogurt maker illustrated in FIG. 7 with that in FIG. 6 andhaving described the earlier embodiments make it apparent that the onlysubstantial difference is that the occluder device is moved to thehousing's top. In this arrangement, the split paddle 701 is moldedintegrally with the cover 702. The motor 703 has its output shaft 704extending upwardly through the tubular center post 705 of the moldedplastic housing 706. This shaft is keyed to a downwardly projecting stem707 of the occluder 708.

The occluder supports a permanent magnet 709 thereon which cooperateswith a magnetic reed switch 710 mounted in a recess of the cover 702when the occluder 708 is in its home position. Also mounted in the cover702 is an electromagnet 712 adapted to cooperate with a permanent magnet711 disposed on the occluder.

In this apparatus, when the motor 703 is driven, it rotates the occludermember 708 which is magnetically coupled to the top 702 by theattractive force between the permanent magnet 711 and the core of theelectromagnet 712. Thus, the top 702 rotates with the occluder and withthe paddle member 701 until a point is reached in the cycle where theyogurt mix begins to firm-up and gel. The gelling of the yogurt mixstalls the paddles 701 and the cover 702 is prevented from rotating.However, the occluder, being driven by the motor 703 breaks the magneticcoupling and rotates out of covering relation relative to the ventopening 713. That rotation of the occluder 708 relative to the top 702also causes the reed switch contact 710 to open to shut off the motor703 and to disconnect the power from the heating element disposed in thesplit paddle 701. Where the unit is disposed in a refrigerator, coolingair passes through the vent 713 to terminate the culturing process. Ifthe unit is to be used on a countertop, then, as with earlierembodiments, the thermoelectric heat exchanger 714 has its powerreversed when the occluder swings independently of the cover so as tofunction in a cooling mode rather than a heating mode.

In any one of the described embodiments, rather than testing theconsistency of the milk product by its viscosity, a pH or chemicalchange measuring device may be used to detect when the hydrogen ionconcentration of the mix reaches a predetermined level of acidity orother chemical change occurs and for automatically turning off thewarming and initiating cooling thereof in response to such condition. Asmentioned earlier, the motor current can be sensed using a comparitorcircuit. As the yogurt gels, the motor current increases and when itexceeds a threshold established by the comparitor, a control signal isdeveloped that can be used to terminate warming and initiate cooling.

Yogurt Starter Introducer

FIGS. 10 and 11 respectively show a side elevational view and a top viewof an attachment for the preceding six embodiments of the inventionwhich allows for the automatic introduction at a predetermined timepoint in the cycle of operation of a yogurt starter mix. The starter mixmay comprise yogurt purchased from a grocery store and may comprise asmall amount of a previously prepared batch of yogurt. The introducercomprises a molded plastic container indicated generally by numeral 1001and, as shown in FIG. 11, it includes downwardly and inwardly slopingend and side walls 1005. Each of these side walls terminates at itslower end in a rectangular base 1006 having an aperture 1007 formedtherethrough. Aligned with this aperture is a downwardly extending tube1008 that is adapted to fit through an opening in the top of the housingof the yogurt maker when plug-in electrical contacts 1009 are fittedinto an electrical jack or socket formed on the cover of the housing.

The electrical contacts 1009 are connected by electrical conductors (notshown) to the terminals of a solenoid device 1010 disposed within acompartment of the device 1001. A hinged lid, as at 1011 is used toclose the container 1001 following the placement of the starter materialwithin the adder device.

The solenoid 1010 is operatively coupled by a linkage 1012 to a shutter1013 that normally occludes the aperture 1007, preventing the startermaterial from flowing down through the tube 1008. Upon the timedactuation of the solenoid 1010, however, the shutter 1013 swings out ofthe way of the aperture 1007 and allowing the starter material to flowthrough the tube 1008 into the container of the yogurt making machine.Rather than employing a solenoid to actuate the shutter 1013, a currentactivated bimetal strip may be used instead.

As should be apparent from what has been described, the device of FIGS.10 and 11 is adapted to be plugged into the sockets 318 of theembodiment of FIG. 3, socket 425 in the embodiment of FIG. 4 and socket626 in the embodiment of FIG. 6. A set of contacts (not shown) in thesolid state timer 810 may be used to complete a circuit between thepower supply and the solenoid 1010 (or bimetal strip) at an appropriatetime when the contents in the container of the yogurt preparing machineare at an appropriate culturing temperature.

This invention has been described herein in considerable detail in orderto comply with the patent statutes and to provide those skilled in theart with the information needed to apply the novel principles and toconstruct and use such specialized components as are required. However,it is to be understood that the invention can be carried out byspecifically different equipment and devices, and that variousmodifications, both as to the equipment and operating procedures, can beaccomplished without departing from the scope of the invention itself.

The above descriptions are thus intended by way of example only and arenot intended to limit the present invention in any way except as setforth in the following claims.

What is claimed is:
 1. A kitchen appliance for automatically makingyogurt from a milk product through a culturing process, comprising:(a) ahousing defining a chamber adapted to be warmed to a predeterminedculturing temperature by an electrical current; and (b) means forautomatically interrupting the electrical current upon the milk productreaching a predetermined cultured state.
 2. The kitchen appliance ofclaim 1 and further including means for automatically imparting coolingto the chamber for the milk product upon interruption of the electricalcurrent.
 3. The kitchen appliance of claim 1 wherein the means forautomatically interrupting the electrical current comprises a means forsensing the consistency of the milk product within the chamber.
 4. Thekitchen appliance of claim 3 wherein the means for sensing theconsistency comprises:(a) a paddle disposed within the chamber andadapted to be at least partially submerged in the milk product; and (b)means for periodically imparting relative motion between the paddle andthe housing.
 5. The kitchen appliance of claim 1 wherein the means forautomatically interrupting the electrical current upon the milk productreaching a predetermined cultured state comprises means for sensing achange in a chemical state of the milk product; andswitching meansresponsive to detection of said changed chemical state of the milkproduct for interrupting the electrical current.
 6. The kitchenappliance of claim 1 wherein the means for automatically interruptingthe electrical current upon the milk product reaching a predeterminedcultured state comprises means for sensing a change in a physical stateof the milk product; andswitching means responsive to detection of saidchanged physical state of the milk product for interrupting theelectrical current.
 7. The kitchen appliance of either claim 5 or claim6 and further including means for automatically imparting cooling to thechamber for the milk product upon interruption of the electricalcurrent.
 8. The kitchen appliance of claim 7 wherein the means forautomatically imparting cooling comprises:means for unblocking a flow ofambient cooling air into the housing.
 9. The kitchen appliance of claim7 wherein the means for automatically imparting cooling is a reversiblewarmer/cooler device disposed in the housing.
 10. The kitchen applianceof claim 1 and further including a container insertable into the chamberfor receiving the milk product therein.